> >>common in today's circuits.  Also, 0.01 uF caps are less expensive and
> take
> >>up less space (0805 vs. 1206).
>
> Huh? Why would you use a 1206 0.1uf for anything unless you needed 50WVDC
> or more rating?
>
> Everything I have read on bypassing for digital says to use 0603 or
> smaller parts since they have lower inductance, and at the moment 0603 is
> the most cost effective. On a current design I have 0603 0.1uf, 0.01uf and
> smaller, 0805 1uf and 1210 10uf ceramic caps, besides the larger
> tantalums.

The operative phrase above is "at the moment".  Well, at the moment I did my
cost/size comparison, 0.01 uF 0805 was cheaper than 0.1 uF 1206 and 0805.  I
suspect this is still the case, at least it was last time I bought a reel of
caps.  I don't use 0603 parts yet, due to lack of need for them.  Maybe soon
though.  You are correct about smaller case size leading to lower
inductance.  I also try to minimize the number of distinct parts used in our
products, to keep inventory manageable and get as much economy of scale
across our product line as we can in a small operation.  When I say small, I
mean we don't produce a blue-purple-zillion units a year like the chip
companies expect us all to do.  Most of us are not in the cellphone and
video game console business!

Whatever happened to the effort to start a Protel User's website with
downloadable footprints and such?  I remember some enthusiatic discussion
about this maybe a year or two ago, but nothing since.  And whatever
happened to Adbul (Abd ul-Rahman Lomax)?  He seems to have dropped of this
list.  Or maybe he is a DXP user now?  Forget Carmen Santiago, Where in the
world is Abd ul-Rahman Lomax?

Best regards,
Ivan Baggett
Bagotronix Inc.
website:  www.bagotronix.com


----- Original Message -----
From: <[EMAIL PROTECTED]>
To: "Protel EDA Forum" <[EMAIL PROTECTED]>
Sent: Tuesday, June 03, 2003 6:45 PM
Subject: Re: [PEDA] six or eight-layer (or more?) stackups - Capacitance





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